Aircraft are generally provided with multiple avionics systems which require one or more antennas to be mounted on the aircraft. Antennas have specific requirements of size, weight, reliability and maintainability. Particularly, size and weight requirements restrict locations where the antenna can be installed because poor antenna placement can degrade the flying qualities of an aircraft and impact the performance of the avionic system. Furthermore, the antenna has reliability requirements and should be capable of withstanding prolonged exposure to the environment. Maintenance requirements are generally expressed in that the antenna should require minimum repair time if a failure occur. Additionally, antennas have limitations regarding to the directions in which radiation intensity is radiated. The avionics systems using antennas provide for example functions such as communication, navigation and radar functions. Communication and navigation functions are typically accomplished by UHF/VHF radios, LOS (Line of sight) communication systems, SATCOM (Satellite communication), Tactical air navigation equipments (TACAN), Instrument Landing Systems (ILS), Global Positioning Systems (GPS) and radar altimeters.
These avionics systems may be of crucial importance for piloting the aircraft. For example, when the aircraft is an unmanned air vehicle (UAV), loss of communication with the UAV may trigger special procedures to be implemented which could result in destruction of the UAV.